1. Field of the Invention
The field of the invention relates generally to remediation and recovery of useful amounts of oil from offshore oil spills in which crude oil is dispersed, emulsified, aggregated, or otherwise entrained beneath the surface. In particular, the field of the invention relates to a cost effective system for recovery of useful amounts of spilled crude oil through subsurface separation based on the difference in specific gravity between the oil and the sea water.
2. Background of Related Art
Oil spill remediation techniques have failed to keep pace with recent advances in offshore oil drilling technology. Deep-sea drilling technology now exists that enables crude oil extraction at previously unattainable depths. Drilling may be accomplished from an anchored, stable floating deep-sea platform, such as at least one platform in the Gulf of Mexico (Peridido) operating at depths in excess of 2400 meters.
anchored, stable floating deep-sea platform, such as at least one platform in the Gulf of Mexico (Peridido) operating at depths in excess of 2400 meters.
Oil spills, particularly those far offshore, and in deep water, are substantially inaccessible to recovery by conventional methods. Spills form deep water wells, particularly when the oil aggregates through sedimentation, may not rise to the surface, and may have serious long term consequences for marine life and marine based economies, and adversely impact the food supply derived from the ocean.
Conventional Remediation Practices do not Work in Deep Offshore Oil Spills.
Over forty years after the Santa Barbara oil spill, conventional remediation measures remain substantially unchanged and ineffectual, and generally are limited to enclosing floating spilled oil with floating booms, skimming oil off the surface, dispersing oil with chemicals, or soaking it up with straw or other absorbent materials when it reaches the shore.
However, choppy water, ocean waves, and strong winds can make it substantially impossible to use the foregoing conventional methods to contain an offshore oil spill. Further, due to the density of crude oil and tendency of oil molecules to agglomerate, sinking may occur due to the adhesion of particles of sediment or organic matter to the oil. In a massive deep ocean offshore spill a majority of the spilled oil may remain submerged below the surface. Such submerged masses of oil are incapable of being contained, much less recovered, by conventional oil spill remediation technology.
Conventional Centrifugal Water-Oil Separation Methods are Prohibitive Due to Cost, Mechanical Complexity, Limited Form Factor, and Undue Energy Consumption.
Conventional centrifugal water-oil separators have serious disadvantages when applied to deep-water recovery of spilled oil that remains submerged below the ocean surface. A centrifugal water-oil separator is a conventional device designed to separate oil and water by centrifugation. It generally contains a cylindrical container that rotates inside a larger stationary container. The denser liquid, usually water, accumulates at the periphery of the rotating container and is collected from the side of the device. The less dense flowable material, usually oil, accumulates at the rotation axis and is collected from the center. See for example; U.S. Pat. Nos. 4,175,040, 4,959,158, and 5,591,340.
Such conventional centrifugation systems have serious disadvantages making them inapplicable for offshore recovery of oil in deep water. The centrifuge devices are mechanically complex and consume considerable energy to rotate the cylindrical container filled with oil and water. Also, such machines are oriented vertically and would need to be deployed on a surface vessel or barge. Thus, their form factor would be limited by necessity. The limited availability of energy offshore, in deep ocean, further would render such devices incapable of performing widespread remediation and recovery of a major, deep water, submerged oil spill.
Submerged oil must be pumped up to such a conventional centrifugal oil-water separator system, thus requiring complex pumping equipment, consuming even more energy in the pumping process, and necessitating additional equipment for underwater containment or entrapment of the oil for pumping. The amount of energy for such a pumping operation would need to be provided by a surface vessel and would prohibit cost effective separation of oil and sea water.
Therefore, what is needed is a new system for offshore oil spill remediation that can be used in deep ocean water, where most of the spilled oil remains submerged below the surface.
What is also needed is a system that is capable not only of entrapping the spilled oil offshore, before it reaches land, but is capable of recovering the oil to a usable state for subsequent refining. Such usable recovery of oil would minimize economic losses associated with the spilled oil itself, and would enable an oil company to recover value from the presently wasted oil. The ability to recover the spilled oil to a usable state also would provide an economic incentive to clean up as much spilled oil as possible.
It also would be desirable to provide a cost effective, system for separating and recovering the oil in a single operation at any desired depth—without the need for an external energy source; saving the energy for pumping the recovered, separated oil to a surface vessel for direct transport to a refining center.